Review request for JDK-8011630 - JSON parsing performance issue

[Hannes Wallnoefer]

Please review JDK-8011630 - JSON parsing performance issue

http://cr.openjdk.java.net/~hannesw/8011630/

This adds new methods in Property and FindProperty to get and set values 
for spill and user accessor properties without creating a method handle.

This reduces parsing time of the huge JSON file from about one minute to 
15 seconds. Most of the remaining overhead seems to be in 
PropertyMap.addProperty().

Hannes